Anchor mechanism for rock drills



July 21, 1964 J. c. LAWRENCE ANCHOR MECHANISM FOR ROCK DRILLS 6 Sheets-Sheet 1 Filed July 51, 1962 INVENTOR. James C. Lawrence BY ig W ATTORNEYS July 21, 1964 J. c. LAWRENCE 3,141,510

ANCHOR MECHANISM FOR ROCK DRILLS Filed July 31, 1962 6 Sheets-Sheet 2 ZNVENTOR James C. Lawrence ATTORNEY 5 July 21, 1964 J. c. LAWRENCE ANCHOR MECHANISM FOR ROCK DRILLS 6 Sheets-Sheet 3 Filed July 31, 1962 James 0. Lawrence ATTORNEYS mm mm 1. q mm 8 a 8 1t MHHEH mm x a m a i ll W m 9 mm MK m C: :3 E. .l Irv .w w Q. E 8 mm mm July 21, 1964 J. c. LAWRENCE 3,141,510

ANCHOR MECHANISM FOR ROCK DRILLS Filed July 31, 1962 s Sheets-Sheet 4 INVENTOR James 0. Lawrence BY w w w ATTORNEYj July 21, 1964 J. c. LAWRENCE ANCHOR MECHANISM FOR ROCK DRILLS 6 Sheets-Sheet 5 Filed July 31, 1962 INVENTOR James 0. Lawrence BY M? ATTORNEYS July 21, 1964 c; LAWRENCE 3,141,510

' ANCHOR MECHANISM FOR ROCK DRILLS Filed July 31, 1962 6 Sheets-Sheet 6 FIG. 10

INVENTOR James C. Lawrence L ATTORNEYS United States Patent 3,141,510 ANCHGR MECHANISM FOR ROCK DRILLS James C. Lawrence, Seattle, Wash assignor to Alkirk,

This invention relates todrills and particularly to novel drill construction and mode of operation cleanly cutting accurate relatively large diameter holes in hard and difficult materials such as thick reenforced concrete slabs.

In its preferred embodiment the invention will be described as' incorporated in a portable concrete drill of novel construction, but the scope of the invention will be expressed in the claims. In this drill an anchor device is inserted into a small pilot bore which has been formed as by a conventional power tool, and a rotating large-diam eter cutting element is essentially pulled into the slab by forces reacting from the anchor device.

It is the. major object of this invention to provide a novel portable drill structure comprising an anchor device and power means coacting with the anchor device to pull a rotating cutting element toward and into the work.

A further object of the invention is to provide a novel drill structure having an anchor device and a special hydraulic system coacting with the anchor device for pulling a rotating cutting element into the work.

Another object of the invention is to provide a drill structure wherein a power driven rotating cutting element is mounted to be longitudinally advanced in a novel manner by a special hydraulic cylinder and piston arrangement.

A further object of the invention is to provide a novel drill structure having an eccentric pistonhydraulic cylinder arrangement for counteracting the torque reaction tending to rotate the drill housing about the drill axis.

A further object of the invention is to provide a novel drill structure wherein the cutting element is driven by an electric motor which'also develops fluid pressure in a special hydraulic self-contained system that advances the cutting element into the work.

Another object of the invention is to provide a concrete or like drill structure having a pilot device for entry and anchoring in a pilot bore, and a novel cooperating hydraulically advanced motor-driven rotating cutting element.

Another object of the invention is to provide a drill structure having a hydraulic system for a cutting element feed and a novel valve arrangement for controlling that system.

Further objects of the invention will appear as the description proceeds in connection with the appended claims and the annexed drawings wherein:

FIGURE 1 is a generally perspective view showinga portable drill according to a preferred embodiment of the invention;

FIGURE 2 is a rear end view of the drill of FIGURE 1;

FIGURE 3 is a section substantially on line 3--3 of FIGURE 4 showing internal structural detail and particularly the piston eccentricity;

FIGURE 4 is a longitudinal section through the drill substantially on line 4-4 of FIGURE 2 showing further internal structure;

FIGURE 5 is a section on line 5-5 of FIGURE 4 showing front details;

FIGURE 6 is a section on line 66 of FIGURE 4 showing valve housing chambers and passages;

FIGURE 7 is a section on substantially line 7.-7 of FIGURE 4 showing the drive gearing locking arrangement;

FIGURE 8 is a partial section substantially on line 88 Patented July 21, 1964 of FIGURE 2 showing valve structure, the valve here being in neutral position;

FIGURE 8A .is similar to FIGURE 8 but shows the valve spoolshifted to the left for feeding the cutting element during operation;

FIGURE 9 is a fragmentary section substantially along line 9-9 of FIGURE 2 showing electrical details; and

FIGURE 10 is an enlarged fragmentary section showing the gear train driving the pump and the cutting element from the electric motor.

Referring to FIGURES 1, 2 and 4, the drill assembly according to a preferred embodiment of the invention comprises a rigid housing 11 to the rear end of which is attached a sturdy rigid handle 12. As shown in FIG- URE 2, handle 12 is .of generally U-shape, and as shown in FIGURE 4 handle 12 extends at right angles to the longitudinal axis of the drill and is preferably hollow for light weight.

Housing 11 is divided by internal walls into a cylinder 13 and a motor housing 14. As shown in FIGURE 3, the longitudinal axis of the, cylinder bore 15' lies in a diametral plane indicated atX--X containing the longitudinal axis of the motor housing.

Cylinder 13 is closed ,at its rear end by a fluid-tight plate. 16, and is closed at its forward end by the upper part 17 of a gear housing 18 which is rigidly secured to housing 11. -In some structures plate 16 is integral with housing 11.

A cylindrical piston 21 is slidably mounted in bore 15, and a cylindrical tube 22 which is rigid with piston 21 projects inopposite longitudinal directions from the piston. As shown in FIGURES 3 and 4, tube 22 is eccentric with respectto bore 15, by a distance noted at e in FIGURE 3, and the longitudinal axis of tube 22 lies in the plane X-X containingthe axes of bore 15 and motor housing 14.

The rear tube section 23 projects slidably through plate 16 at bore 24 which has an O-ring seal 25 with the tube.

The end of tube section 23 slidably abuts endwise a wingtype locking nut 26 having a threaded bore 27 by which it is rotatably mounted on an externally threaded locking sleeve 28.

Sleeve28 extends freely entirely through tube 22 and piston 21, which latter is suitably apertured to freely pass sleeve 28. As shown in FIGURE 4, sleeve 28 terminates remote from'the housing 11 and abuts a hollow spacer 29.

An anchor rod 30 extends longitudinally slidably all the way'through sleeve 28 and the piston21, and rod 30 has a short threaded front terminal 31 where it emerges from sleeve'28. Rod' 31) has a short rear threaded portion' 32 adapted to 'threadedly mount a nut-like button 33 which is adapted to abut the rear end of sleeve 28. A retainernut 34 is also threaded on the end of rod 30 for abutment with the button 33.

At the front end of rod 30, a cylindrical annulus 35 of rubber or like resilient material which expands'radially when compressed longitudinally is freely mounted on rod 30, and a nut 36 on threaded rod end 31 locates annulus 35 in endwise abutment between nut 36 and the fiat front end of surrounding spacer 29. Normally the outer diameters of sleeve end 23, annulus 35 and nut 36 are substantially equal so that they may slidably enter a pilot bore, and it will be seen that by relative longitudinal movement of rod 30 and sleeve 28 the annulus 35 will be subjected to axial pressure and, since rubber is incompressible, the annulus 35 will expand radially fora purpose to appear. In the illustrated embodiment, when button 33 is rotatedclockwise, it shifts rod 30 to the right in FIG- URE 4 relative to sleeve 28 to expand sleeve 35.

Disposed in the motor housing 14 is a-motor-36 comprising afield coil assembly 37 mounted on the housing in surrounding relationship to a rotor 38 supported at 3 opposite ends in housing bearings 39 and 41. A fan 40 is non-rotatably mounted on shaft 42 for cooling motor 36. The motor shaft 42 projects forwardly into a gear chamber 43 where it is formed with an integral gear 44 (FIGURE Referring to FIGURE 10, gear 44 is meshed With a gear 45 non-rotatably mounted on a stub shaft 46 having its opposite ends journaled in housing bearings 47 and 48 and formed with an integral gear 49 meshed with a gear 51 which in turn is non-rotatably mounted on a shaft 52 supported at opposite ends in housing bearings 53 and 54. Non-rotatably mounted on shaft 52 is a gear 55 that is meshed with a gear 56.

Gear 56 (FIGURE 4) is supported on the housing 18 by closely adjacent roller bearings 57 and 58, one on each side. An elongated rear hub 59 of gear 56 extends rotatably into a housing bore 61 where it is surrounded by O- ring seals 62 and 63. An elongated front hub 64 of gear 56 extends rotatably through a fluid-tight seal 65 in the bore 66 of the boss 67 of a housing front end closure plate 68 secured to gear housing 18 by studs 69 that have their inner ends threaded into housing 11 (FIGURE 10).

Bearings 57 and 58 are so mounted on the housing as to retain gear 56 in axially fixed position while permitting free rotation of gear 56 and its hubs 59, 64 in concentric surrounding relation to sleeve 28 which does not rotate with the gear 56.

At its front end, hub 64 is splined at 71 to non-rotatably mount a clutch disc 72 which is connected by clutch ring 73 to a driving disc 74. Disc 74 is rotatably mounted on hub 64 and is drive-connected to disc 72 by an axial pin 75 rigid with disc 74 and axially slidable in bore 76 of disc 72. The end of hub 64 is turned over at 77 to lock the clutch discs axially on hub 64, with clutch ring 73 in frictional drive transmitting engagement with opposed beveled surfaces 78 and 79 on the clutch discs.

The rigid front end 81 of piston extension tube 22, which extends freely through the gear 56, carries an internally projecting radial key 82 coacting slidably with a longitudinal slot 83 on sleeve 28, and a similar radial key 84 on rod 30 slidably coacts with slot 83 in axially spaced relation to pin 82. This prevents relative rotation of tube 22, sleeve 28 and rod 30 but permits relative axial movement between all three of them.

At the front end of tube 22, a spider 91 is mounted on a support 92 non-rotatably secured upon the beveled front end 93 of the tube. A plurality of equally spaced axial projections 90 are provided on spider 91. A plurality of radial bearing pins 94 (preferably three) extend outwardly from the spider, being adjustably radially secured thereon as by set screws 95, and the outer bearing surfaces 96 of these pins lie in a cylindrical envelope.

A hollow cylindrical drill element 97 is mounted to extend between clutch discs 72, 74 and the spider assembly, and this drill terminates in an annular cutting face 98 usually incorporating imbedded diamonds or like abrasive. Drill 97 is rotatably supported and guided at its front end on bearing surfaces 96, and is supported and driven at its rear end by frictional engagement with clutch ring 73 and a force fit on clutch disc 74. Thus, when gear 56 is driven, the drill 97 is rotated.

Hydraulic System Housing 18 contains a pump chamber 101 in which is disposed a driven gear type pump element 102 meshed with gear 55 and carried by a shaft 103 rotatably mounted in opposed bearing bores in the housing 18 and closure 68. The housing 18 is formed with a pump discharge passage 104 from which hydraulic liquid under pressure from chamber 101 is forced. Passage 104 is also shown in FIGURE 7 and FIGURE 8.

Referring now to FIGURE 8, passage 104 is aligned with a passage 105 in housing 11, and branch passages 106 and 107 lead therefrom to spool valve 108 which is 4 slidable in bore 109 and actuated by a stem 111 having a handle 112.

Bore 109 is formed with an enlarged chamber 113 intermediate and open to both branch passages 106 and 107 in the neutral spool valve position of FIGURE 8. In this position of the spool, chamber 113 is connected through radial spool port 114, axial passage 115 and radial port 116 to one end of housing passage 117. The other end of passage 117 is shown in FIGURE 4 as opening into the cylinder bore 15 at port at the left end of piston 21.

Referring back to FIGURE 8, valve chamber 113 is connected by passage 118 in housing 11 and aligned passage 119 in housing 18 to gear housing chamber 121 which in turn is connected by passage 122 (FIGURE 4) to gear chamber 43. The lower end of chamber 43 is connected by annular passage 123 (FIGURES 4 and 10) to reservoir chamber 124 which contains an accumulator piston 125 biased by spring 126. It will be noted that passage 123 is formed in a removable end wall 120' for the motor housing 14. Hydraulic fluid from chamber 43 returns to the pump intake through internal wall bore 127 (FIGURE 10).

Spool 108 has spaced lands and 128 which cooperate to control flow from passages 106 and 107 as will appear, and a further throttling land 129 about midway between lands 127 and 128.

When valve spool 108 is located in neutral position, as shown in FIGURE 8, hydraulic fluid (oil) is circulated continuously when motor 36 is activated. Oil under pump pressure from chamber 101 is delivered through passages 104, 106 and 107 to the valve chamber 113.

Part of this oil under pressure passes through spool port 114, passage 115 and spool port 116 to passage 117 which ports at 120 into cylinder bore 15 to the left side of piston 121 in FIGURE 4.

Another part of this oil under pressure passes through a radial spool port 131, axial passage 132 and radial spool port 133 to enlarged cross-section passage 134 in housing 11. Passage 134 is connected to the right hand end of bore 15 by means of a passage 135 (FIGURE 8) that ports at 136 (FIGURE 4) into the cylinder 15.

The remainder of this oil under pressure passes from chamber 113 through passages 118 and 119 back into the valve housing into the reservoir 124 and to the pump inlet.

Thus, when the valve spool is in this neutral position the oil fills all of the housing passages and the cylinder bore 15, and all of the oil is at substantially the same pressure so that there is no displacement of piston 121. The accumulator piston 125 maintains a pressure of about three to five pounds on the oil in the reservoir and gear housing passages to insure that an adequate supply of oil is delivered to the pump when the drill is used in other positions than with its axis vertical.

When it is desired to advance the rotating drill element 97 into work such as a concrete slab, the handle 112 is pushed inwardly. This shifts the spool valve 108 to the left in FIGURE 8, and the parts assume the position of FIGURE 8A when the spool shoulder 130 abuts the end of bore 109 at housing 18.

Now passage 107 is cut off and oil from branch passage 106 enters bore 109, most of it passing through port 114, passage 115 and port 116 to passage 117 and port 120 where it reacts between the left face of piston 121 and the adjacent surface of housing 18.

It will be noted that, as shown by the arrow in FIG- URE 8A, some of the oil passes to chamber 113 and so to the other side of piston 121 through the annular orifice 140 that exists between spool land 129 and the adjacent edge of bore 109. This orifice 140 changes in size as the spool 108 is displaced axially, and this throttles the flow of oil to chamber 113 in such a manner that the more spool 108 is displaced to the left in FIGURE 8(8A) the higher will be the developed oil pressure at port 120.

Thus it will be seen that the hydraulic pressure exerted at the left (forward) side of the piston 21 is proportional to the amount of manual (axial) displacement of handle 112. In this manner, as will appear, the operator may control the drill pressure on the Work.

Similarly when the handle 112 is retracted rearwardly from the neutral position of FIGURE 8, the spool 108 is displaced to the right in FIGURE 8 and new branch passage 106 is blocked by land 127, and throttling land 129 now coacts with the edge of bore 109 at the right side of chamber 113 in FIGURE 8 to provide an annular throttle orifice similar to that at 140 to throttle the flow of oil entering chamber 113 from passage 157 and develop a higher pressure in the oil in passage 134 and in the cylinder 15 at the right side of piston 121 in FIG- URE 4. As with orifice 140, this orifice likewise varies in size with the axial position of spool 108, although since this-takes place during drill withdrawal from work, as will appear, it is usually desirable that land 129 quickly blocks off flow of any oil from passage 107 into the chamber 113 at this time.

Referring back to FIGURE 4, attached to the right end of motor housing 14 is a motor control switch assembly 151 comprising a casing 152 containing a snap switch 153 controlled by push button 154. When button 154 is pushed inwardly, to the left in FIGURE 4, the circuit of motor 36 is energized and motor 36 rotates the pump element 161 and the drill element 97 as long as the button 154 is held in. When button 154 is released the switch is opened by a suitable spring contact arrangement therein to break the motor circuit.

Motor housing 14 is formed with internal cooling passages 141 through which water or the like may be circulated as by a hose attached to inlet plug 142 and a suitable outlet (not shown).

FIGURE 7 shows a built-in assembly feature. A looking pin 155 is axially slidably mounted in a hollow plug 155 threaded into an opening 157 that leads from an external recess 158 of housing 18 into the space 159 surrounding shaft 52. Shaft 52 has a diametral opening 161 adapted to receive the inner end of pin 155 when the pin has been displaced to the dotted line position of FIGURE 7. A compression spring 162 engaging a shoulder 163 on pin 155 normally maintains the pin 155 in its inactive full line position of FIGURE 7. An O-ring seal 164 prevents an oil pressure leak along pin 155.

The ultimate function of pin 155 is to hold gear 56 and the clutch disc assembly at 72, 74 stationary when drill element 97 is to be removed therefrom. This is done by pushing in pin 155 to enter shaft'opening 161 and thereby lock the gear train to the clutch.

Operation When the drill assembly is to be used, a suitable sized drill element 97 is mounted on the clutch disc 74. If the drill is to provide a hole in a thick slab of concrete, for example, the diameter of the drill end at 98 is the diameter of the hole to be formed.

First, a small diameter pilot hole is drilled into the slab at the center of the desired hole. This may be done by any conventional hand or power tool or bit and usually about /4" to 1" diameter, in any.event large enough to slidably receive the anchor rod end pilot structure at 36, 35, 29.

Then, assuming the concrete slab to be horizontal, the drill assembly of the invention is centered over it, and the pilot structure at 36, 35, 29 advanced into the pilot bore. The distance that the pilot assembly extends into that hole is determined by manual rotation of the locking nut 26. It will be seen that as nut 26 is rotated in the proper direction the sleeve 28 will be axially displaced to the left in FIGURE 4. Sleeve 28 does not rotate because of the key and slot connection at 84, 83 and the eccentricity of piston 121.

With the pilot structure properly axially located in the pilot bore, it is now anchored against axial displacement. This is done by rotating button 33 whereby rod 30 is positively displaced to the right in FIGURE 4 to axially compress rubber annulus 35 and cause it to radially expand into tight gripping engagement with the pilot bore wall. Then the entire piston assembly is locked to the slab in axial alignment with the pilot bore by rotating nut 26 which shifts the piston assembly to the left relative tosleeve 28 in FIGURE 4 until the spider projections tightly abut the surface of the slab. Now the drill assembly is rigidly anchored in alignment with the pilot bore and in position to drill the main bore or hole in the slab.

The operator with his hands on handle 12 first pushes in button 154 to energize motor 36. This drives the pump to pressurize the oil system with the housings 1S and 11, and starts rotation of the tubular drill element 97.

Now the operator acts to feed the rotating drill element into the slab. This is done by pressing inwardly (to the left in FIGURE 4) on the spool valve handle 112 and drilling pressure is maximum when approximately the position of FIGURE 8A is attained. The drilling pressure may be proportioned to suit the material being cut by the degree of displacement of the modulating spool valve. At this time the oil pressure on opposite sides of the piston is unequal, the greater pressure being exerted upon the inner or left side of the piston in FIG- URE 4. Up to fifty times manual pressure is easily available. However, piston 121 now cannot be displaced since the above-described anchored pilot structure locks it to the slab. Hence the entire housing 11 including the motor and driven parts on it is displaced and pulled to the left in FIGURE 4, advancing rotating cutting element 97 into the slab. As the cutting element 97 moves relative to the anchored piston and rod unit, it slides longitudinally over bearing surfaces 96 and it cuts out a circular plug from the slab. Assuming the slab to be six inches thick, a clean smooth-walled circular hole will be formed therein of the diameter of cutting element end 98 when the cutting element has advanced six inches, and when valve handle 112 is moved to the opposite position from FIGURE 8A to withdraw the element 97 the concrete plug will be extracted with the element leaving the hole clean and open. In practice, cutting element 97 may have a diameter up to fourteen inches.

An important feature of the invention is the eccentric offset of the anchored piston tube 22 relative to cylinder bore 15. This insures that as the rotating cutting element is entering the slab during cutting, the torque reaction tending to oppositely rotate the housing 11 will be counteracted and it is easier for the operator to hold the drill assembly over the hole. The operator merely retains his hands on handle 12 with his fingers controlling switch button 154 and valve handle 112, and he exerts no downward pressure on the drill.

The tremendous pressure developed within the drill assembly, reacting from the anchored front end of sleeve 28 essentially pulls the rotating cutter element 97 into the slab.

The drill of the invention may be used in spaces that are normally inaccessible to large diameter hole-forming devices now available, such as ceilings, fioor corners and high walls. Also it may be used by a contractor to form clean holes where desired in cast concrete floors, for example, eliminating the need for expensive architectural detailing of such holes for electrical conduits and special coring.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. In a drill for forming a hole in relatively solid material, a housing, a drive motor mounted on said housing, means forming a longitudinally disposed cylinder in said housing, a piston slidably mounted in said cylinder, a cutting member rotatably mounted on said housing on an axis parallel to said cylinder, anchor means extending longitudinally through said housing comprising an anchor section disposed to enter a pilot bore in said material and means for actuating said anchor section after it has been introduced into said bore to interlock tightly with the bore wall, means operatively connecting said piston to said anchor means, and means defining a hydraulic system in said housing having a pump driven by said motor and a selector valve for introducing hydraulic fluid under pressure into said cylinder in operative association with said piston to effect relative longitudinal displacement between said anchored piston and said housing and movement of said cutting member relative to said material.

2. In the drill defined in claim 1, said housing containing gearing connecting the motor to said pump and said cutting member, and means within the housing directing circulation of said hydraulic fluid to lubricate said gearing.

3. In a drill for forming a hole in relatively solid material, a housing, a drive motor mounted on said housing, means forming a longitudinally disposed cylinder in said housing, a piston slidably mounted in said cylinder, a tubular cutting member rotatably mounted on said housing on an axis parallel to said cylinder, anchor means extending longitudinally through said cutting member comprising a radially expansible section disposed to enter a pilot bore in said material and means for expanding said section after it has been introduced into said bore, means operatively connecting said piston to said anchor means, and means defining a hydraulic system in said housing having a pump driven by said motor and a selector valve for introducing fluid under pressure into said cylinder in operative association with said piston to effect relative longitudinal displacement between said anchored piston and said housing and movement of said cutting member relative to said material.

4. In a drill adapted to form a hole in relatively solid material, a housing, an electric motor mounted on said housing, means forming a longitudinally disposed cylinder in said housing, a piston slidably mounted in said cylinder, a tubular cutting member rotatably mounted on said housing on an axis parallel to said cylinder, anchor means extending longitudinally through said piston and said cutting member comprising an anchor section disposed to enter a pilot bore in said material and means for anchoring said section after it has been introduced into said bore, means operatively connecting said piston to said anchor means, and means defining a hydraulic system in said housing having a pump driven by said motor and a selector valve for introducing fluid under pressure into said cylinder in operative association with said piston to effect relative longitudinal displacement between said anchored piston and said housing and movement of said cutting member relative to said material.

5. In the drill defined in claim 4, said piston having opposite tubular longitudinal extensions slidable in end Walls of said cylinder, and said anchor means extending through said piston and extensionsv 6. In the drill defined in claim 4 a final drive gear rotat able with said cutting element journalled'on said housing in surrounding relation to the forward piston extension. 7

7 In a drill for forming a hole in relatively solid ma- 'terial, a housing, an electric motor mounted on said housing, means forming a longitudinally disposed cyl inder in said housing, a piston slidably mounted in said cylinder, a tubular cutting member rotatably mounted on said housing on an axis parallel to said cylinder, anchor means extending longitudinally through said piston and said cutting member comprising a radially expansible section disposed to enter a pilot bore in said material and means for expanding said section after it has been introduced into said bore, means operatively connecting said piston to said anchor means, and means defining a hydraulic system in said housing having a pump driven by said motor and a selector valve for introducing fluid under pressure into said cylinder in operative association with said piston to efiect relative longitudinal displacement between said anchored piston and said housing and movement of said cutting member relative to said material.

8. In a drill for forming a hole in relatively solid material, a housing, an electric motor mounted on said housing, means forming a longitudinally disposed cylinder in said housing, a piston slidably mounted in said cylinder, a tubular cutting member rotatably mounted on said housing on an axis parallel to said cylinder, an anchor rod extending longitudinally through said piston and said cutting member, radially expansible means on said rod disposed to enter a pilot bore in said material and means for expanding said expansible means after it has been introduced into said bore, means operatively connecting said piston to said anchor means, and means defining a hydraulic system in said housing having a pump driven by said motor and a selector valve for introducing fluid under pressure into said cylinder in operative association with said piston to effect relative longitudinal displacement between said anchored piston and said housing and movement of said cutting member relative to said material.

9. In the drill defined in claim 8, a sleeve extending through said piston in surrounding relation to said rod and said means for expanding said expansible means comprising means for relatively axially moving said rod and said sleeve.

10. In a drill for forming a hole in relatively solid material, a housing, a motor mounted on said housing, means forming a longitudinally disposed cylinder in said housing, a piston slidably mounted in said cylinder, a cutting member rotatably mounted on said housing on an axis parallel to said cylinder, anchor means extending longitudinally through said piston and said cutting member comprising an anchor section disposed to enter a pilot bore in said material and means for anchoring said section after it has been introduced into said bore, means operatively connecting said piston to said anchor means, and means defining a hydraulic system in said housing having a pump driven by said motor and a flow modulating valve for controlling introduction of fluid under pressure into said cylinder in operative association with said piston to effect relative longitudinal displacement between said anchored piston and said housing and movement of said cutting member relative to said material.

11. In apparatus for forming a hole in relatively solid material, a housing, a drive motor mounted on said housing, means forming a cylinder in said housing, a piston assembly slidably mounted in said cylinder on an axis eccentric to the cylinder axis, a cutting member rotatably mounted on said housing on an axis parallel to said cylinder, means for anchoring said piston assembly directly to said material, means for operatively rotating said cutting member from said motor, said eccentric piston and cylinder arrangement resisting the drive torque reaction during rotation of said cutting member by said motor, and means for introducing hydraulic fluid under pressure into said cylinder to displace said rotating cutting member relative to said material.

12. In the apparatus defined in claim 11, said cutting member rotating coaxially of said cylinder.

13. In a drill for forming a hole in relatively solid material, a housing, a motor mounted on said housing, means forming a longitudinally disposed cylinder in said housing, a cutting member rotatably mounted on said housing and connected to be rotated by said motor, a piston slidably mounted within said cylinder and having rigid tubular eccentric extensions projecting slidably through said housing at both ends of said cylinder, an anchor rod extending through said extensions and cylinder, a sleeve surrounding said anchor rod and extending through said extensions and cylinder, radially expansible means on the front end of said rod beyond the end of the adjacent piston extension, means at the rear end of the cylinder for actuating said sleeve to radially expand said radially expansible means to lock said anchor rod within a pilot bore in said material, means including said sleeve and rod for locking said piston directly to said material, and a hydraulic system in said housing having a pump driven by said motor and a selector valve controlling the application of fluid pressure to opposite sides of said piston in said cylinder to displace said rotating cutting member With respect to said material.

14. In a drill for forming a hole in relatively solid material, a housing, a motor driven cutter unit mounted on said housing, means forming a longitudinally disposed cylinder in said housing, a piston assembly slidably mounted within said cylinder and having rigid tubular extensions projecting slidably through said housing at both ends of said cylinder for reciprocable displacement on an axis eccentric to the cylinder axis, an anchor rod extending through said extensions and cylinder, a sleeve surrounding said anchor rod and extending through said extensions and cylinder, a resilient sleeve on the front end of said rod, means at the rear end of the cylinder for relatively axially displacing said sleeve and rod to radially expand said resilient sleeve to lock said anchor rod within a pilot bore in said material, adjustable means on said sleeve reacting against the anchored rod for forcing the piston assembly into tight abutment with said material and positioning said cutter unit in alignment with said pilot bore, and means for introducing fluid under pressure into said cylinder to displace said cutter unit relative to said material.

15. In a drill for forming a hole in relatively solid material, a housing, a motor in the housing, a cutting element rotatably mounted on the housing and drive connected to said motor, means forming a cylinder in said housing, a piston assembly slidable in said cylinder, anchor means extending through said piston to enter a pilot bore in said material, means for actuating said anchor means to grip a Wall of said bore, adjustable means for forcing said piston assembly into tight interlock with said material after said anchor means has been actuated to align said cutting element with said pilot bore, and means for introducing hydraulic fluid under pressure into said cylinder for displacing said cutting element relative to said material.

16. In the drill defined in claim 15, said cutting element being a hollow cutter coaxial With said cylinder, and said piston assembly being slidable on an axis parallel to but eccentric with respect to the cylinder axis.

17. In a drill for forming a hole in relatively solid material, a housing, a motor in the housing, a cutting element rotatably mounted on the housing and drive connected to said motor, means forming a cylinder in said housing, a piston assembly slidable in said cylinder, means for anchoring said piston assembly to the material to be drilled by said cutting element, means for introducing fluid under pressure into the cylinder for displacing said housing and the cutting element carried thereby relative to said anchored piston, and cooperating means on the anchored piston assembly and cylinder for counteracting drive torque when the motor is rotating said cutting element in cutting engagement with said material.

18. In the drill defined in claim 17, said means for introducing fluid pressure into the cylinder comprising a relatively closed hydraulic circuit within the housing containing a pump, a reservoir and a manually actuated control valve.

19. In the drill defined in claim 17, said drive connecting between the motor and cutting element comprising gearing within said housing, one of the gears having a hub projecting from the housing and the cutting element being supported on said hub.

References Cited in the file of this patent UNITED STATES PATENTS 1,152,337 Nelson Aug. 31, 1915 2,879,034 Cowan Mar. 24, 1951 

3. IN A DRILL FOR FORMING A HOLE IN RELATIVELY SOLID MATERIAL, A HOUSING, A DRIVE MOTOR MOUNTED ON SAID HOUSING, MEANS FORMING A LONGITUDINALLY DISPOSED CYLINDER IN SAID HOUSING, A PISTON SLIDABLY MOUNTED IN SAID CYLINDER, A TUBULAR CUTTING MEMBER ROTATABLY MOUNTED ON SAID HOUSING ON AN AXIS PARALLEL TO SAID CYLINDER, ANCHOR MEANS EXTENDING LONGITUDINALLY THROUGH SAID CUTTING MEMBER COMPRISING A RADIALLY EXPANSIBLE SECTION DISPOSED TO ENTER A PILOT BORE IN SAID MATERIAL AND MEANS FOR EXPANDING SAID SECTION AFTER IT HAS BEEN INTRODUCED INTO SAID BORE, MEANS 